Custom Computer Wont Boot

I have a computer that was running fine until I needed to move it into a new case. I took all of the parts out of the old case and put them in the new one but now it is not working properly. The only part I changed was the graphics card which I swapped out for a new evga 8400 gs. The problem is that when I hit the power all of the case fans and gpu fan starts up as well as the hard drive but noting even shows up on the monitor. At first I thought it was an issue with the graphics card but then I realized that the cpu fan is not spinning. Everything used to work fine before so im not sure where to start to see what is causing the issue.

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